How to mitigate the risk of servicing discount vouchers after date of expiry at POS level?

The Point-of-Sale (POS) system must be robust enough to enable the user to set up “red flags” via user-friendly graphical interface. Discount vouchers “inventory” should be updated in real time manner, and vouchers should have a bar-code that must be scanned prior to honoring them.

by making special ofter to goods which Approached its expiration date